The perennial question is "will my [insert ferment] give me botulism?" Or I read a lot of "I heard [insert food] can give you botulism." I've heard so much of this I finally decided to do some real digging into these claims, and write this article. I've read through all the CDC botulism reports from 2001-2010 (this and last year are not available), and several detailed incident reports to find out what all the scare is about. Hopefully this will help dispel any misconceptions.

First let's get an overview of what botulism is. Botulism is an illness that causes varying degrees of paralysis in the body from a toxin produced by the bacteria Clostridium botulinum. C. botulinum is practically everywhere - just about anything that's touched soil will contain spores. So why don't we get sick from it all the time? Most of the time this bacteria is dormant, and it's only when conditions are right that it grows and makes this toxin. C. botulinum prefers an anaerobic (oxygen-free) environment that's not too acidic, not too salty, not too crowded with other bacteria, and it does especially well at warm temperatures. A unique characteristic of C. botulinum is it's ability to survive high temperatures for relatively long periods of time.

Fermenting foods creates an environment that is antagonistic to botulism. It's what scientists call "competitive exclusion." Beneficial bacteria begin to acidify the food, a condition C. botulinum doesn't like. Adding salt to a ferment also reduces C. botulinum's ability to grow, and encourages beneficial bacteria to take over. There are also other "competitive factors" that beneficial bacteria and fungi create in smaller quantities to exclude pathogenic varieties.

So how often does botulism really occur in fermented foods? According to the CDC reports the leading causes of botulism are (in order of significance):1) Home-canned foods using improper canning technique (by far #1)2) Commercially prepared/distributed foods (pasteurized and/or preserved)3) Improperly stored/handled cooked food (at home and in restaurants)4) Fermented meats and fish (almost all reports from Alaska)5) Unkown (very low incidence of undetermined sources)

I did not find a single incident of fermented vegetables, sauerkraut, kimchi, lacto-fermented pickles, kombucha, lacto-sodas, kvass, kefir, yogurt, cheese, etc. The only anomaly was a single case of "fermented" tofu, whereupon reading the detailed report it's clear that the tofu didn't actually ferment - it only marinated in chicken broth, coated in vegetable oil at room temperature for several days after having been cooked.

Fred Breidt, USDA specialist, on fermented vegetables: "There has never been a documented case of foodborne illness from fermented vegetables. Risky is not a word I would use to describe vegetable fermentation."*

So will your sauerkraut give you botulism? NO.

MEATS AND FISH: Practically all the CDC reports of fermented meats and fish were from Alaska, things like buried salmon, beaver tail, seal fat. Fermented meats and fish are a special case. Animal flesh is high in proteins and fats, and very very low in carbohydrates and sugars. The beneficial bacteria need these carbohydrates to thrive. If you plan to ferment meats, it's wise to learn from credible sources. Sandor's book The Art of Fermentation has a whole chapter dedicated to this. If his book doesn't answer any immediate questions, it's well annotated with resources. But meats can be safely fermented.

READ THE FINE PRINT: There's been chatter going around about botulism and carrot juice. Once the dreaded word "botulism" gets linked to some food, people seem to assume there's significant and inherent risk in this food. But nobody bothers to read the fine print. First read the instructions on the upper right, then look carefully at the lower right corner of the label below:This year (2012) and in 2006 the CDC reported incidents of botulism connected with commercial bottled carrot juice. Products from both incidents were pasteurized. So here's what we've really got: a highly nutritious substrate for microbes, no salt added to encourage salt-loving bacteria or discourage pathogens, low acidity (none added, no fermentation), and it gets heated (pasteurized) just to a point that many (if not most) the good bacteria are killed, but not hot enough to kill C. botulinum.

So carrot juice by itself doesn't give you botulism. Unfermented carrot juice that has been pasteurized, bottled, and sat in a warm truck for an undetermined period of time might.

A FINAL NOTE: Approximately two-thirds of botulism cases reported to the CDC are cases found in infants. These are not considered food-related cases because infants' gut flora has not yet developed to compete with the pathogens we unwittingly ingest everyday. So eat your sauerkraut!

Thanks for a very good review of the literature and facts regarding fermentation. I do both hot canning and fermentation of vegetables. I do check the pH of my hot canned vegetables,if trying a new recipe. C. botulinum does like heat much more than L. acid and salt solution.

Fred Breidt, USDA specialist, on fermented vegetables: "There has never been a documented case of foodborne illness from fermented vegetables. Risky is not a word I would use to describe vegetable fermentation."*

Tim, could you please help me with this?I just bought tomato juice in a glass jar, tasted and only then noticed it was spoiled, sour, and actually bubbling in the jar (!),(the exp. date is fine),do you think the bubbling should cause special alarm?I called the manufacturer, they'll check but couldn't say anything else,should I be concerned with botulism?or could be just spoiled with other non-botulism stuff?I know this is not ur main thing, but right now you know more than most I know..thanks,Ido

Could there be other, non-botulism things growing in there? For sure, especially if the seal had been broken. Clostridium is less common in acidic foods (tomatoes), but it can still be present. Best I can tell you is don't freak out, pay attention to your body, and if you have any problems get medical attention ASAP. Also you might just do an internet search on the brand of tomato sauce, and see if you turn up any reports on it. Information moves fast nowadays.

I was wondering about pasteurized fruit juice. It seems like whenever we buy some, it tends to go off before we can get around to drinking it all. Yes, we keep it in the fridge as instructed. It's just bottled fruit juice, pasteurized but nothing else added, not even from concentrate.

Would it be possible to extend the shelf (fridge) life of the pasteurized juice if I added a touch of live culture to it, just a few drops? Something like Whey from yoghurt cheese, or sauerkraut juice?

Doing my best to be the change I want to see in the world, one meal at a time.http://wholewheatfsm.blogspot.ca

it's funny you mentioned that, cause that's exactly what I'm trying to play with, make a juice kinda like tomato juice but with ferment etc..I have a flavor in mind but ain't there yet...I was busy cutting tomatoes, that's why I missed the "explosion" of that bottled muck.. :)